1. Field of the Invention
This invention relates to an electric power conversion apparatus used for an electric vehicle driving apparatus or an inverter apparatus, and in particular, to structure for miniaturization and weight reduction, and advanced functionality of drive and protection means of a semiconductor device for electric power conversion, failure diagnosis, or the like.
2. Description of the Related Art
In the electric vehicle, in particular, an electric motorcar, or a hybrid car, the miniaturization and weight reduction of an inverter apparatus for three-phase motor drive are required for a mounting space and fuel cost reduction. Generally, an inverter apparatus consists of an electric power conversion apparatus for converting a DC voltage into an AC voltage, and a controller that controls a three-phase motor. Usually, they are contained in separate cases respectively due to problems of heat generation and switching noise of the semiconductor device for electric power conversion.
As for the electric power conversion apparatus, an intelligent module where a high-speed semiconductor device represented by an IGBT and a circuit for driving and protecting the IGBT are integrated has been already produced commercially. For example, as shown in Japanese Patent Laid-Open No. 5-137339, the structure of arranging an IGBT drive and protection circuit board on a semiconductor device is disclosed.
In addition, as for a controller, a high-performance microcomputer is usually used, and arbitrarily controls the rotation speed, torque, and electric power of a three phase motor by inputting a line current, a rotating speed, etc. of the three phase motor from dedicated sensors and performing data processing, and giving a switching signal to a gate terminal of a semiconductor device in the electric power conversion apparatus. In addition, although a pulse width modulation waveform called PWM is used as a switching signal waveform given to a gate terminal of a semiconductor device for electric power conversion, since it is general technique, detailed explanation will be omitted here.
In the configuration of a conventional inverter apparatus, as shown in FIG. 18, an electric power conversion apparatus 123 including a signal insulation circuit 115a and a U phase arm typically showing only one phase of three phases, and a controller 121 including a microcomputer 114a etc. are respectively contained in separate cases. However, a power supply 122 supplying power to an IGBT drive and protection circuit board is also contained in a case different from these due to problems of heat generation and noise. In addition, the U phase arm includes a UH phase (upper arm U phase) drive and protection circuit 117a, a UL phase (lower arm U phase) drive and protection circuit 118a, and switching devices 2a and 2b and free wheel diodes 3a and 3b as electric power conversion devices. Reference numeral 20 is a three-phase motor.
The power supply 122 which includes an waveform shaping circuit 26 and an insulation type power supply circuit 116a and supplies power to an IGBT drive and protection circuit board may be integrated in an IGBT drive and protection circuit board in an intelligent module in the case of that with comparatively small power capacity. Nevertheless, since the current capacity of the power supply circuit itself also becomes large in that with large power capacity, the power supply circuit is contained in a case different from an intelligent module due to a cooling method of suppressing heat generation of a power transformer etc., and a problem of a board mounting space.
In addition, since a malfunction of an electronic component mounted on the board is induced due to the influence of electromagnetic noise at the time of IGBT performing switching operation, it is devised to simply obtain the effect of electromagnetic shielding in a conventional IGBT drive and protection circuit board by arranging all the electronic components on the top surface (C side) of the board and making the back surface (S side) fully grounded. On the other hand, since only one side of the board becomes the mounting space of electronic components, this becomes a struggle of raising a degree of integration and functions of the IGBT drive and protection circuit.
As described above, a power supply of an IGBT drive and protection circuit cannot be integrated with an intelligent module in a conventional apparatus due to problems of heat generation and switching noise of a semiconductor device, and a board mounting space. Hence, there is a disadvantage that it is not possible to miniaturize an electric power conversion apparatus, and in extension, an inverter apparatus itself.